The present disclosure relates to semiconductor-on-insulator (SOI) structures, and particularly to SOI structures in which a cap layer comprising a boron-rich compound or doped boron nitride is located between a top semiconductor layer and a buried insulator layer.
Semiconductor-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) technology is currently being considered for a variety of aerospace/military electronic applications. In space systems, exposure to high fluxes of electrons and protons can significantly reduce system lifetime due to total ionizing dose (TID) effects. Ionizing radiation can induce significant charge buildup in oxides and insulators leading to device degradation (e.g., threshold voltage shifts) and failure. This radiation effect has become one of the most important issues affecting the reliability of integrated circuits (ICs) in near earth orbits.
In SOI ICs, a thin semiconductor layer such as, for example, silicon is formed over an insulator layer, such as silicon oxide, which in turn is formed over a substrate. This insulator layer is often referred to as a buried oxide (BOX) layer or simply as a BOX. Total dose response of SOI circuits can be very complicated due to the presence of the buried oxide in an SOI substrate. Total dose radiation-induced back-channel leakage can occur as positive charge trapped in the buried oxide of SOI ICs near the silicon/oxide interface and can cause large increases in IC static power supply leakage current. For a fully-depleted SOI transistor, such as a FinFET and a trigate device, where a top-gate transistor is electrically coupled to a back-gate transistor, radiation-induced charge buildup in the buried oxide will directly affect the top-gate transistor characteristics. In view of the above, there remains a need for providing improved SOI structures and methods to mitigate TID effects.